Lighting devices are known in which primary light is partly converted into secondary light having a longer wavelength by means of a phosphor. In this case, the phosphor is arranged remote from the primary light source, which is also referred to as “remote phosphor”. The phosphor then emits a mixed light having a portion of non-converted or unconverted primary light and a portion of the secondary light as useful light. In the case of blue primary light, blue-yellow-converting phosphor and hence yellow secondary light, a blue-yellow or white mixed light may be generated. If the phosphor volume is damaged (e.g. owing to the occurrence of cracks and/or holes in the phosphor volume), the primary light can radiate through the phosphor volume undesirably to an intense degree. The lighting device may then emit primary light having a high intensity, which brings about undesired lighting effects or can even cause damage to health, e.g. eye damage from direct viewing of the lighting device. This disadvantage is particularly pronounced when a laser is used as primary light source.
It is known to use a light sensor in order to detect an intensity of the mixed light generated by means of the primary light source and thereby to determine a case of damage of the phosphor volume on the basis of sensor data of said light sensor by means of an evaluation unit. What is disadvantageous here is that, when there is a case of damage, within the period of time that elapses until the case of damage has been recognized, the intensive primary radiation can emerge from the lighting device.